I always assumed the metallic aftertaste I got after long coding sessions was unrelated.
http://www.jmargolin.com/xy/xymon.htm
http://www.jmargolin.com/vgens/vgens.htm
Asteroids was a humble 6502 running at 1.5 MHz with a PROM-driven pseudo-CPU acting as the vector generator.
The limitation shifted elsewhere of course, and that's in the complexity of the scene, specifically the number of objects.
Still, interesting tech and can even be adapted to control a laser unit that renders on say a big building or even the clouds (the real ones).
There are other limitations, such as beam deflection imprecision and precision/speed of the A/D converter and the size of the electron beam in relation to it's brightness. Tighten the beam focus to get more precision, but it will be way dimmer and harder for a player to see. Make the beam stronger to compensate and you'll burn a hole in the phosphor. Your costs also go up with the fancier parts and beefier power supply.
The Atari system settled on 1024 points of resolution on each axis (but clipped to 1024x768 for the 4:3 monitors used at the time). Still a lot more resolution than the low-res arcade monitors of the day, which were roughly CGA-class (around 320x240).
Laser galvo speed is a big factor in making it work effectively but there have been some great demos, like John Knoll (from ILM) playing Atari Star Wars on a theatre screen:
The vector display sits face up in the bottom of the cabinet, and the game is reflected on a one-way mirror set up in front of a backdrop. Those super-bright vector graphics are even more impressive when they look like they're floating!
There was a rumour that people who played on a Vectrex (a vector display home console) would experience eye damage after protracted sessions.
Has anyone recently played with an old Asteroids cabinet? The screen is a black and white CRT. When you fire a missile, the screen effect is insanely bright. I'd forgotten just how intense that was.
I can't wait until someone pieces together an art piece that makes use of all the crazy analog video effects that we used to take for granted, but now look like alien technology.